Polymer-based piezoelectric composite material, piezoelectric film, piezoelectric speaker, and flexible display
The present invention provides a polymer-based piezoelectric composite material from which a piezoelectric film capable of outputting a higher sound pressure and exhibiting excellent flexibility even in a low-temperature environment is obtained in a case of using a piezoelectric speaker, a piezoelectric film formed of the polymer-based piezoelectric composite material, and a piezoelectric speaker and a flexible display which are formed of the piezoelectric film. The polymer-based piezoelectric composite material of the present invention is a polymer-based piezoelectric composite material including a polymer matrix which contains a polymer containing a group represented by Formula (1), and piezoelectric particles. *-L 1 -(CR 1 R 2 ) n —CN Formula (1) In Formula (1), L 1 represents a divalent linking group excluding a urethane group. R 1 and R 2 each independently represent a hydrogen atom, an alkyl group, or an aryl group. n represents an integer of 3 or greater. * represents a bonding position with respect to the main chain of a polymer.
1. A polymer-based piezoelectric composite material comprising:
a polymer matrix which contains a polymer containing a group represented by Formula (1); and
piezoelectric particles,
*-L 1 -(CR 1 R 2 ) n —CN Formula (1)
in Formula (1), L 1 represents a divalent linking group excluding a urethane group, R 1 and R 2 each independently represent a hydrogen atom, an alkyl group, or an aryl group, n represents an integer of 3 or greater, and * represents a bonding position with respect to a main chain of a polymer.
2. The polymer-based piezoelectric composite material according to claim 1 ,
wherein the polymer has a repeating unit represented by Formula (2),
L 1 , R 1 , R 2 , and n in Formula (2) each have the same definition as that for L 1 , R 1 , R 2 , and n in Formula (1), and
R 3 represents a hydrogen atom or an alkyl group.
3. The polymer-based piezoelectric composite material according to claim 2 ,
wherein L 1 represents —O—, —S—, —CO—, —NH—, or a group formed by combining two or more thereof, where a urethane group is excluded.
4. The polymer-based piezoelectric composite material according to claim 2 ,
wherein the polymer is a polymer having only a repeating unit represented by Formula (2) in which n represents an integer of 3 to 5 or a polymer having a repeating unit represented by Formula (2) and a repeating unit containing a polar group other than a cyano group.
5. The polymer-based piezoelectric composite material according to claim 1 ,
wherein a content of the piezoelectric particles is 50% by volume or greater with respect to a total volume of the polymer-based piezoelectric composite material.
6. The polymer-based piezoelectric composite material according to claim 1 ,
wherein the piezoelectric particles include ceramic particles having a perovskite-type or wurtzite-type crystal structure.
7. The polymer-based piezoelectric composite material according to claim 6 ,
wherein the piezoelectric particles contain any of lead zirconate titanate, lead lanthanum zirconate titanate, barium titanate, zinc oxide, or a solid solution of barium titanate and bismuth ferrite.
8. A piezoelectric film comprising:
the polymer-based piezoelectric composite material according to claim 1 ; and
two thin film electrodes laminated on both surfaces of the polymer-based piezoelectric composite material.
9. A piezoelectric speaker comprising:
the piezoelectric film according to claim 8 .
10. A flexible display comprising:
the piezoelectric film according to claim 8 that is attached to a surface of a flexible display having flexibility on a side opposite to an image display surface.